1. Technical Field
The present invention generally related to monitoring devices for pneumatic tires and, more particularly, to monitoring devices that are loosely disposed within the pneumatic tire and free to movement about bounded only by the rim and the tire mounted to the rim. Specifically, the present invention relates to the structure of a non-attached monitoring device that lifts the central portion of the monitoring device away from the footprint of the tire when the monitoring device is positioned in the footprint of the tire.
2. Background Information
Various type of tire monitoring devices are known in the art. Known monitoring devices are embedded within the tire, mounted to a surface of the tire, mounted to the rim (or the valve stem), or are loosely disposed within the tire. A common problem with the in-tire monitoring devices is that the tire and rim attenuate radio frequency transmissions from within the tire.
Various solutions have been proposed to improve radio frequency transmissions from with a tire. These solutions include boosting the power of the transmitter and improving the configuration of the antenna. In non-attached monitoring devices, the problem of radio transmissions through the tire is significant when the non-attached monitoring device is resting in the footprint of the tire because the monitoring device is next to the ground and immediately adjacent the steel belts disposed in the crown of the tire. Another problem with existing monitoring devices is that liquid disposed in the tire can attenuate the radio transmissions when the antenna of the monitoring device is disposed under the upper surface of the liquid.